In return for the exchange, White has the bishop pair, a great knight on d4, pressure on the queenside, and the black knight is trapped on a2. The computer gives its traditional equality assessment, but in practice the position is difficult to play for Black. Some positions are \"more equal\" than others.
15... e6a2  16. a1a2  16... b4a2  17. c1d2  17... f8d8 